Disc changer with  safe and efficient disc handling! top drive transfer mechanism applying variable force tangential to top edge of disc being transferred

ABSTRACT

Automatic disc changer apparatus includes a tray containing elastomeric grooves designed to securely hold multiple compact information storage discs in generally upright positions, one or more stations, each performing processing operations on discs transferred from the tray one at a time (operations such as reading information from discs and/or writing information to them), mechanism for effecting relative movement between the tray and the stations for aligning a selected groove in the tray with a station, a transfer mechanism associated with each station for moving a disc from the selected groove to a loading position at the station, and from that position back to the tray, in controllably driven rotations, and latch mechanism for laterally moving the disc between the loading position and a processing station. In the controllably driven rotation, top and bottom edges of each selected disc are flexibly constrained while a force is applied to the disc tangential to its top edge. After processing, the selected disc is returned to the tray in a controllably driven reverse rotation. In the rotation from the loading position back to the tray, the selected disc may be returned to the tray either at the groove position from which it was previously removed or a different groove position.

This application is a continuation of U.S. application Ser. No.08/464,408, filed Jun. 5, 1995, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to automatic disc changers; particularly thoseof the type wherein multiple data discs are held in close proximity, ina common receptacle or tray, and transferred one at a time between thetray and a processing station (typically, a location where informationis read from and/or written to the discs).

Discs of the type presently contemplated include those commonly known ascompact discs (CD's), which are used to store digital information forcomputers (e.g. digital data and computer programs), and informationrepresenting reproducible audio and/or video presentations that do notrequire a computer for reproduction. Such compact discs may havediffering recording formats and playback protocols, and different namesindicating their usage; e.g. names such as CD-ROM (compact disc--readonly memory), CDR (compact disc--recordable), etc. Their names,recording formats and playback protocols have no specific relevance tothe present invention.

The present invention is concerned particularly with providing automaticdisc changer apparatus, and an associated method of disc handling, thatis safer and more efficient than known prior systems.

Terminology

Controlled drive: (also "controllably driven") connotes transfer ofdiscs over a defined range, by edge drive, with bottom and top edgesconstrained in a manner allowing the rate of movement to be optimizedthroughout the range, without compromising disc safety.

Disc Reader: a unit such as a CD-Rom drive, for performing a processingaction on discs including actions such as reading and writing.

Safe and efficient: connotes efficient handling of discs withoutcompromising the integrity of storage; "efficient" connoting quick andcost-effective handling of large numbers of discs (e.g. 400 discs in adisclosed preferred embodiment).

Station: position or place containing a disc reader and a platform fromwhich discs are moved to the reader and to which discs are moved fromthe reader.

Idle Station: a station not holding a disc, and not in the process ofloading or unloading a disc (see Loading and Unloading below).

Transfer: connotes movement of a disc between a tray and a station.

Loading: transfer of a disc from a tray to a station.

Unloading: transfer of a disc from a station to a tray.

2. Prior Art

Presently known automatic disc changer systems are rather expensive andslow acting. For example, one known system has an average access time(the time for locating a disc and transferring it to a station) on theorder of 15 seconds. Such systems also are constrained by safetyconsiderations to handle fewer discs than would be desired in manyapplications.

PRINCIPAL OBJECTIVE OF THE INVENTION

This invention seeks to provide an automatic disc changer system that issafer and more efficient than prior art systems. In the precedingsentence, "safer and more efficient" is intended to mean havingcapability for handling a given number of discs with less risk of damage(or loss of recorded information) than comparable prior systems, andalso having capability for safely handling more discs than priorsystems, provide faster access to individual discs than prior systems,and be made at favorable cost in comparison to prior art systems.

SUMMARY OF THE INVENTION

The present invention includes a tray for holding multiple discs inclose proximity to each other, one or more processing stations, a discpositioning assembly for effecting relative movement between the trayand station(s) to align a selected disc in the tray with a station, adisc transfer assembly for moving selected discs between the tray andstation, one at a time, in controllably driven rotational movements (seeTerminology discussion above), and a load/unload assembly for moving theselected discs between the transfer assembly and a processing positionat the station (e.g. a position in which the disc is securely mounted ona freely rotatable spindle for interaction with reading and/or writingapparatus).

In a system with a single station, the disc positioning assembly is usedto prepare a selected disc for transfer to that station by the disctransfer and load/unload assemblies of that station. In a configurationwith plural stations, each station has an associated disc transferassembly and load/unload assembly; and the disc positioning assembly isoperated to position a selected disc for transfer between the tray and anearest "idle" station. An idle station in the foregoing context, is onethat is currently not holding a disc and not engaged in the process ofloading or unloading one (see Terminology above).

The tray has a large capacity (e.g. for holding 400 compact discs) andspecially constructed grooves for holding the discs in close proximityto each other. The grooves, which are formed in a relatively softelastomeric polymer medium, elastically "pinch" individual discs alongtheir bottom edges. The tray may have either a circular or rectangularshape. If the tray is circular, the positioning assembly effectsrotational relative movement between the tray and station(s). If thetray is rectangular, the positioning assembly effects linear relativemovement between the tray and station(s).

Each disc transfer assembly overlies the tray and the (respective)station, and operates to move discs bidirectionally, one at a time,between the tray and (respective) station in controllably drivenmovements in which top and bottom edges of the disc are controllablyheld and guided throughout the movement. Each load/unload assembly is ator proximate to the (respective) station and operates to move the discbidirectionally between the transfer mechanism and a processing positionat the station (e.g. a position in which the disc is mounted upon aspindle that is freely rotatable for presenting the disc for interactionwith reading and/or writing equipment). When the load/unload assemblyreceives a disc from the (respective) disc transfer assembly, thedisc/transfer assembly is operated to disengage itself from contact withthe disc.

Each transfer assembly of this invention operates to securely hold andguide top and bottom edges of a disc throughout each transfer movement,and to apply a time varying force to the top edge of the disc that iseffective to quickly yet safely accelerate the disc at the start of eachtransfer, and quickly yet safely decelerate the disc at the end of eachtransfer. The elastomeric gripping and guiding of the disc at its topand bottom edges permits the disc to be accelerated and deceleratedfaster than would otherwise be safely feasible.

In a preferred embodiment described below, each transfer mechanismincludes a topdrive assembly that contacts the top edge of the discduring transfer, and a level stage between the tray and respectivestation that contacts the bottom edge of the disc while the disc is intransit between the tray and the load/unload assembly.

A groove in the stage forms a supporting and guiding channel for thebottom edge of the disc during transfer handling. The groove in thestage is aligned with the desired path of movement of the disc, and isformed in an elastomeric polymer that is harder than the material inwhich the grooves in the tray are formed. Thus, the groove in the stageholds and guides the bottom edge of the disc during a transfer,preventing the bottom edge from rolling out of the required transferpath, but it does not "pinch" the respective edge so as to potentiallyimpede the transfer (or increase the force required to move the discover the stage).

The topdrive assembly includes an arm carrying a pair of pulleys thatsupport a flexible belt. The arm and belt overlie both the discs in thetray and the station, and they are movable as a unit to position thebottom surface of the belt in contact with the top edge of a (selected)disc in the tray, as well as to disengage the belt from such contactwhen the respective disc has been transferred to the (respective)load/unload assembly. The belt is aligned with the station and itsbottom surface (that contacts the top edge of a disc during transfer) isshaped in an inverted V formation that serves as a guiding channel forthe top edge of a disc during each transfer. The V formation in the beltserves to center top edges of opposite surfaces of the disc and therebykeep the disc vertically aligned during the transfer movement.

One of the pulleys is linked to a bidirectional step motor that isactivated when the belt is in contact with the top edges of a disc beingtransferred. This moves the belt linearly relative to the disc it iscontacting, to exert a driving force along the top edges of that discwhich causes the disc to rotate in a direction determined by theactivated step motor (from the tray towards the station during loading,and from the station towards the tray during unloading).

Each "disc holding" groove in the tray has a bottom portion shaped as acircular arc congruent to an arc portion of a disc, and side portionsthat aligns to the groove in the stage when the tray and stage aresuitably positioned for transferring a disc from the respective groovein the tray to that in the stage. As shown in the preferred embodiment,wherein stations are on different sides of a circular tray (inside theinner periphery and outside the outer periphery) or on different sidesof a rectangular tray, each groove in the tray has side portionsextending symmetrically from the bottom portion to positions at whichthe disc would move from the tray to stages positioned on differentsides of the tray. Each side portion of a groove in the tray isgradually inclined towards a respective side of the tray, so as tomoderate the force required to move a disc up from the bottom portion ofthe respective groove in the tray and out onto the groove in a stagelocated on the respective side of the tray.

As a safety feature, the groove in the stage and inverted V formation inthe belt are designed (in form and relative hardness) to prevent contactwith lateral surfaces of the disc inside of a predefined (and generallystandardized) non-recording margin close to the disc periphery.

During downward movement of the arm and belt at the start of a loadingtransfer (from tray to station), an aligning sub-assembly (of thetransfer assembly) is actuated to ensure that the top edge of the discselected to be transferred is suitably aligned with the belt to seatsecurely in the guiding channel formed by the inverted V in the belt.The aligning sub-assembly includes a pick carried on the end of the armand a comb pivotally mounted adjacent to and outside the tray at aposition aligned with the station.

As the arm descends, the pick engages and rotates the comb causing apair of tapered teeth on the latter to sweep upward across a side edgeof the disc facing the comb. The comb teeth are formed to reliablycapture the disc between them, and to straighten out either surface ofthe disc if either surface is misaligned in relation to the planeintersecting the V groove in the belt and the middle of the respectiveholding groove in the tray. Furthermore, the comb teeth are sized tominimize contact with surfaces of the disc inside of a non-recordingmargin close to the periphery of the disc, and formed of a frictionlessplastic material (e.g. DELRIN. Delrin is a registered Trade Mark ofDupont de Nemours Company) to minimize friction between the comb and thedisc.

A feature of the foregoing aligning sub-assembly is that its operationis coordinated with that of the topdrive belt during disc loading so asto retract the comb from the disc as the latter is driven onto thestage, so that the tray can be repositioned while the loading transferis being performed.

At the beginning of each loading transfer, the disc contacted by thebelt moves up the incline in its holding groove onto the stage, and thebelt and arm follow upwardly. This upward movement of the arm retractsthe pick, allowing the comb to fall back to its initial idle position,in which the teeth of the comb are outside of the path of movement ofthe tray and its discs. Thus, as soon as a disc is transferred out ofthe tray to the stage, the tray can be moved to reposition its grooves.In a single station system, this repositioning can be used for instanceto (quickly) establish a new holding position in the tray for a discjust removed from another holding position. In a system with pluralstations, this repositioning is useful for instance to permit the systemto start positioning a second disc relative to a second (idle) stationbefore completion of the process of loading a first disc into a firststation.

In a preferred embodiment to be described, the tray is moved by abidirectional driving mechanism to align discs for transfer to pluralstations. It is also considered feasible to move the stations, and theirrespective transfer and load/unload assemblies, relative to a non-movingtray to accomplish the same disc positioning function; and alternateembodiments involving such configurations are described.

In the preferred embodiment a circular tray (carousel) holding manycompact discs e.g. 400 discs is rotatably positioned relative to e.g. 8stations, each station having respective transfer and load/unloadassemblies. The tray has inner and outer peripheries forming concentriccircles, and the transfer assemblies and load/unload assemblies of eachstation are aligned with radii of these circles. Four of the stationsand their transfer and load/unload assemblies are located inside theinner periphery of the tray, and the other four stations and theirassemblies are located outside the outer periphery of the tray. Thus,the tray and stations are packaged to efficiently use almost all of thespace required to house the tray alone.

In this embodiment, the discs are held in the tray in uniquelystructured disc holding grooves that are uniformly spaced and alignedwith the radii of the tray peripheries, and the tray is rotatedclockwise and counter-clockwise to align a selected disc holding groovewith a station that is to process a disc currently seated in theselected groove. The direction of rotation of the tray is chosen to movethe selected groove to the idle station closest to that groove at thetime of selection (i.e. before the tray is rotated); thereby reducingthe average "seek" time for aligning discs to be transferred. As notedpreviously, the controlled handling of disc transfers between the trayand stations allows the transfer movements to be performed in less timethan they otherwise could. Thus, apparatus according to this embodimenttends to have a short average time for accessing individual discs (suchtime including the sum of average seek time and average transferhandling time).

Along its inner periphery, the tray is supported for rotation by fouruniformly positioned eccentric ball bearings. The underside of the trayis supported for rotation by eight load-bearing pads. The bearingscontacting the inner periphery are covered in polyurethane and formedinto "tire rim" configurations dovetailing with and riding alongmatching projections at the inner periphery of the tray. The loadbearing pads under the tray are made of high molecular weightpolyethylene presenting high-slip (very low friction) surfaces to theunderside of the tray.

Rotational movements of the tray to align discs with stations areactuated by a bidirectional step motor through a special arrangement ofgears and timing belts linked to the outer wall of the tray. Teeth ongears linked to the step motor mesh with inside teeth on a double sidedgear belt, the latter having outside teeth meshing with teeth containedon a single sided belt permanently attached to the outer wall of thetray. A feature of this arrangement is that the step motor and itslinkage to the tray are designed so that an even multiple of unit stepmovement of the step motor displaces the tray by the distance separatingtwo adjacent disc holding grooves. As a result of this arrangement, astandard stepping motor, and off-the-shelf 5 pitch linking components(gears, timing belts, etc.) can be used to position the tray (one costsaving), the positioning assembly can be reliably operated "open loop"to position the tray (another cost saving in comparison to closed loopsystems), the number of grooves (discs) that can be accommodated on atray of given size is optimized, and the positioning assembly can bemade to have a direct correlation in its movements with groove spacingsat the tray periphery simplifying the positioning controls (by allowingfor specification of an even multiple number of step motor steps todisplace the tray by a corresponding number of groove spaces betweendiscs, instead of requiring a complex computation to convert groovedisplacements of the tray into fractional increments of the step motor,etc.).

Another feature of the foregoing tray positioning arrangement is thatthe teeth or the inside and outside of the double sided timing belt areformed with differing profiles in order to mesh intimately with both theteeth on the driving gears and the teeth on the outer wall of the tray.

The present invention can contain from one to eight stations, dependingupon cost and speed considerations (the more stations, the shorter theaverage positioning time for aligning a disc to a station).

The load/unload assemblies mentioned above have a number of uniquefeatures. They have unique structures for moving a disc laterallybetween respective transfer assemblies and spindles which rotates thedisc for processing (reading and/or writing), which structures alsoserve to secure the disc at critical phases of the loading and unloadingactions. In the loading action, these structures act to secure the discas it is removed from engagement with the respective transfer assemblyand mounted on the spindle, and then free the disc and spindle forunencumbered rotation. In the unloading action, these structures act tosecure the disc as it is being disengaged from the spindle, and thenrelease the disc for return to the tray as the disc is controllablyengaged by the respective transfer assembly.

The foregoing structures also include elements acting to balance forcesexerted on the disc as it is moved between the transfer assembly andstation spindle so as to prevent undue flexing or warping of the disc.

In addition to performing read and write processes relative to thediscs, the stations and associated transfer and load assemblies can beused to hold discs for repositioning. In such operations, a disc istransferred to a station from a selected first groove in the tray, heldin the station while the tray is positioned to align a selected secondgroove in the tray with the respective transfer assembly, and the discis then unloaded to the second groove. As noted earlier, an aligningsub-assembly, which ensures vertical alignment of a disc as it is beingengaged by the topdrive belt in preparation for loading, is operated incoordination with the topdrive belt so as to permit repositioning of thetray even before the disc is fully loaded into the station. Thus, in theforegoing disc holding and repositioning application, the time requiredfor moving the disc between first and second grooves in the tray can besignificantly shortened.

In alternate embodiments briefly described herein, a station togetherwith its transfer and load/unload assembly are rotated relative to atray constituting an arc portion of the carousel characterized above,and a rectangular tray is positioned linearly relative to one or morestations together with respective transfer and load/unload assembliesarranged on opposite sides of the tray and its path of movement.

The foregoing and other objects, features, advantages and benefits ofthis invention will be more fully understood by considering the detaileddescription and claims to follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top elevational view of a preferred embodiment of theinvention containing eight processing stations and a circular discholding tray rotatable relative to all of the stations.

FIG. 2 is a side elevation, partly in section, of a part of theapparatus shown in FIG. 1, showing details of the disc holding tray anda transfer assembly associated with a station inside the inner peripheryof the tray; the illustrated transfer assembly being shown in an idle orrest position relative to the tray and its discs.

FIG. 2A shows in elevation details of an aligning sub-assemblyassociated with the transfer assembly shown in FIG. 2 (viewed from thetray).

FIG. 2B is a transverse section through two adjacent grooves in the discholding tray shown in FIG. 2. One of the grooves is shown empty and theother is shown holding a disc in order to indicate how the discs fitinto the grooves.

FIG. 2C shows a sectional profile of the flexible belt that is part ofthe transfer assembly, and serves to contact and drive top edges ofdiscs during loading and unloading transfers.

FIG. 2D is a sectional profile of the tray taken along a singledisc-holding groove.

FIG. 2E is a sectional view of the stage transverse to a disc guidinggroove therein.

FIG. 2F is an enlarged view of a shelf structure at the load position.

FIG. 3 is a side elevation like that in FIG. 2 but showing the transferassembly in a "pick out" position in which an aligning sub-assembly isoperating to ensure alignment of a disc selected to be transferred outof the tray.

FIG. 4 is a side elevation like that in FIG. 3 but showing the transferassembly in a load position in which it is still in contact with a discafter having moved the disc into position for further latching movementby a load/unload assembly of the respective station. FIG. 5 is a sideelevation like that in FIG. 4 but showing the transfer assembly in aread/write position in which it is disengaged from contact with a discthat is ready to be latched into a processing position (wherein the discis secured to a rotatable spindle and disengaged from contact withelements of the load/unload assembly that otherwise would prevent thedisc from rotating with the spindle).

FIG. 6 is a sectional end view of the station shown in FIGS. 2-4, forexplaining the construction and operation of a respective load/unloadassembly as the latter is receiving a disc from the respective transferassembly and preparing to move the disc into the above-mentionedprocessing position.

FIG. 7 is a topview of transfer and load/unload assemblies shown in thepreceding figures.

FIG. 8 is a top view of the load/unload assembly, showing it in anidle/rest position when the respective station and transfer assembly areidle.

FIG. 9 is a top view of the same load/unload assembly, showing it in aposition in a "cocked" position in which its fingers are positioned tointercept a disc currently being moved towards them by the respectivetransfer assembly.

FIG. 10 is a top view of the same load/unload assembly showing itsoperational position just as it receives a disc that is still in contactwith the transfer assembly.

FIG. 10A is a transverse section of the foregoing latch sub-assemblyillustrating its construction.

FIG. 11 is a top view of the load/unload assembly showing it operated tomove the disc laterally into engagement with a rotatable spindle at therespective station reader.

FIG. 12 is top view of the load/unload assembly showing it operated to aprocessing position wherein the disc and spindle are freely rotatableand finger elements in the respective load/unload assembly, which inFIGS. 10 and 11 are in contact with and temporarily holding the discalong a marginal portion of its recordable surface, are pivoted out ofcontact with the disc to permit the disc to rotate freely.

FIG. 13 is a top elevational view of an alternative embodiment of theinvention containing four processing stations and a circular discholding tray with grooves constructed and arranged to be oblique to theradial edge of said tray.

DETAILED DESCRIPTION

Construction and operation of a preferred embodiment of the inventionare explained in numbered paragraphs 1-9 below. Alternate embodimentsare briefly discussed thereafter.

1. General

Referring to FIG. 1, disc changing apparatus in accordance with apreferred embodiment of the invention includes circular tray 1,containing disc holding compartments formed by grooves indicatedgenerally by lines 2. In this embodiment, the tray contains 400 suchgrooves for holding up to 400 compact discs. Tray 1 has an outerperiphery 1a and inner periphery 1b. These peripheries form concentriccircles. The grooves 2 are aligned with radii of these concentriccircles.

The apparatus also includes eight processing stations 10s through 17s,and eight associated disc transfer and load/unload assemblies 10tthrough 17t (10t associated with 10s, 11t with 11s, 12t with 12s, etc.).Each said processing station is mounted on a processing station base 28a(for modular insertion and removal). Four of the stations (11s, 13s, 15sand 17s) lie and are orientated outside the outer circular periphery 1aof the tray, and the other four stations (10s, 12s, 14s and 16s) arelocated and are orientated inside the inner circular periphery 1b of thetray. In the embodiment shown in FIG. 1, the transfer and load/unloadassemblies are all aligned with radii of the concentric circles formedby the tray peripheries.

As noted earlier, discs are selectively transferred from the tray to thestation, one at a time, and the station performs a process relative toeach disc. Typically, the process involves reading information from orwriting information to the disc; however, the process also may consistof holding the disc while repositioning the tray, so as to allow fortransfer of a disc from one groove position in the tray to another one.

The foregoing elements are supported on a base indicated generally at28, and housed within a covering enclosure having sides suggested at 29.Not shown in FIG. 1, but constituting parts of the overall apparatus,are power supplies furnishing electric current needed to operate movingparts and sustain station processing and other functions (such aslogical digital functions needed to control the apparatus and tointerface it to external computer systems and the like requiring accessto information stored on the discs), as well as cooling elements neededto maintain a dust free environment for the discs and a thermally stableenvironment for all of the equipment.

A single sided timing belt 30 (see FIG. 7), permanently secured to theouter periphery 1a of the tray, links the tray to indexing assembly 32.Assembly 32 is coupled to a not-shown bidirectional drive stepper motor.When access to a disc is required, the stepper motor is actuated todrive assembly 32, causing the tray to rotate until the required disc isaligned with a closest idle or other preferred station. Assembly 32contains gears 33, 34 and 35, and a double sided timing belt 36. Teethon gears 33-35 mesh with teeth on the inside of timing belt 36, andteeth on the outside of timing belt 36 mesh with teeth on timing belt30. One of the gears 33 is coupled to the above-mentioned stepper motorand operated by the latter to transmit motion to the tray via belts 30and 36 and the other gears.

The gears and timing belts are standard commercially available partsdesigned for 5 pitch incremental movement (5 teeth per inch). Thepredominant English standard has a center to center distance (tooth totooth) of 0.197 inches. The Metric equivalent used in the preferredembodiment is 5 mm between centers of adjacent teeth. The circumferenceof the tray's outer periphery is 2000 mm and is chosen so that a singlepitch increment of movement of the timing belt 30 attached to the traydisplaces the tray at its outer periphery by exactly 5 mm. The spacingbetween centers of adjacent grooves 2 is made to be exactly 5 mm at theouter periphery. The step motor and its linkage to the tray peripheryare chosen to produce exactly a 5 mm displacement at the tray outerperiphery. A cost saving feature in this arrangement, is that standardoff-the-shelf 5 pitch components (gears, timing belts, etc.), has acharacteristic increment of a movement of 5 mm.

Another advantage is that to position a given groove in the tray to astation that is currently N grooves distant from the given groove (N aninteger), requires specification to the step motor of a number M that isan integer multiple of N, and the step motor can then be operated "openloop" to perform the positioning (rather than requiring a complexcomputation to convert N to a number of displacements that is notdirectly related to the tray groove spacing, and possibly requiringclosed loop control of the positioning itself), regardless of whetherthe station is inside the tray or outside of it.

The foregoing usage of standard stepper motor and 5 pitch elements intray positioning hereafter is termed the 5 pitch feature. It has beendetermined that employing a pitch less than or greater than 5 pitchprobably could be used in establishing tray groove spacings; but suchusage would probably be more costly to manufacture than 5 pitch, lessefficient in terms of the number of grooves that could be placed on atray of given size for purposes presently contemplated, possibly morecomplex in the requirements for controlling tray positioning, andpossibly even require closed loop control of the positioning. Forexample, a pitch e.g. greater than 5, would not yield enough space tofabricate greater than 5, would not yield enough space to fabricate of aCD.

As noted earlier, tray 1 contains 400 grooves that are by the trayperipheries. The number of grooves and their spacing is selected tocoincide with increments of tray movement produced by an even multipleof step increments of operation of the step motor. Thus, increments ofstep motor movement required to align a groove containing a selecteddisc with a designated station are specifiable directly in terms of amultiple of the number of groove spaces between the selected groove andthe designated station. This eliminates the complex computations usuallyrequired to convert desired increments of movement of an objectpositioned by a step motor to increments of step motor displacement thatare not directly related to increments of object movement.

When access to a particular disc in tray 1 is required, and assuming therespective disc is not immediately aligned with an idle station (seeTerminology above), the tray is rotated clockwise or counterclockwise toalign the groove containing the selected disc with an idle station. Thedirection of tray rotation preferably is chosen to align the requireddisc with a closest idle station, so as to reduce the average "seek"time for effecting such groove aligning functions. When the groovecontaining the selected disc is suitably aligned, the transfer assemblyof the respective station is actuated to perform a loading transfer inwhich the disc is first rotated--in a controllably driven manner--fromthe tray to a respective load/unload assembly--and then moved laterallyby the load/unload assembly into a reading position at the processingstation; e.g. into latched engagement with a rotating spindle at thereader. After processing of the disc at the reader, the disc istransferred laterally by the load/unload assembly to the transferassembly, and then returned to the tray in a in a driven unloadingrotational movement that is the reverse of the loading transfermovement.

Along a wall forming the inner periphery 1b of tray 1, four uniformlypositioned polyurethane coated eccentric ball bearings 1c, riding alonga dovetailing "rim" 1b' in the tray inner wall 1b (see FIG. 2), act as"tires" supporting rotation of the tray at that wall. Eight load bearingpads 1d, made of high molecular weight polyethylene present high slip(very low friction) surfaces to the underside of the tray as

2. Tray Groove Profiles

As seen in FIGS. 2 and 2D, tray 1 is a composite structure consisting ofa core 50 of lightweight metal (e.g. aluminum) overcoated with a layer52 of elastomeric polymer containing the grooves 2 in which the discsare held. In these figures, the shape of a single groove 2 is seen inrelation to the bottom edge 53 of a disc 54. As indicated by the 45degree angle markings at 55, each groove is shaped to engage a disc overabout a third of its circumference. As seen in FIG. 2B, each groove 2has a V-shaped cross section tapering to a width less than that of adisc.

Discs are seated in the grooves with sufficient force to ensure that thediscs are firmly held in upright positions and cannot shift out of theirpositions during rotations of the tray. In such seating, bottom edges ofthe discs penetrate into tapered portions of the grooves, distorting theelastomer around each groove to produce an "elastic pinching effect"holding the disc securely in place. The distorted elastomer tends tostore energy enabling it to return the groove to its original shape whenthe disc is removed. This stored energy is manifested as a forceproducing the just-mentioned elastic pinching effect.

Near the tray peripheries 1a and 1b, each groove tapers away from theedge of the disc as shown at 56 and 57 (FIG. 2) to angular inclinationsthat are deliberately formed to be not more than 40 degrees relative tothe horizontal. When transferred to a station, the disc must be drivenup one of these inclines; the one at the outer periphery 1a if thestation is outside the tray's outer periphery, or the one at the innerperiphery 1b if the station is inside the tray's inner periphery.

It has been noted empirically that as the steepness of the grooveincline increases, the initial speed of transfer movement must begeometrically decreased in order to avoid possible unstable movement ofthe disc as it clears the edge of the tray (for example, the disc could"jump", as it moves from the tray to the stage if driven up an inclineat excessive speed, allowing the bottom edge of the disc to slip orslide uncontrollably, or allowing the top edges of the disc to losecontact with the transfer assembly belt (see below) with resulting lossof driving control over the disc rotation. It also has been noted thatinclines around 40 degrees allow for optimization of the initialstarting speed consistent with stable and safe disc handling.Accordingly, it is preferred that the inclines between the tray groovesand the stages over which the discs rotate during transfer (see below)be shaped to about a 40 degree angle relative to the horizontal.

The "elastic pinching" effect noted above serves not only to prevent thediscs from slipping out of their grooves during rotations of the tray,but also to prevent the discs from slipping rotationally as they aredriven up respective groove inclines during disc loading operationsdescribed below.

3. Transfer Assembly

Some aspects of "inside" processing station 11S and its associated dischandling (transfer and load/unload) assemblies 11T are viewable in FIGS.2-5. Since all stations inside the inner tray periphery have identicalconstructions, these views are fully representative of the constructionsof stations 11S, 13S, 15S and 17S and their respective disc handlingassemblies 11T, 13T, 15T and 17T. Giving due consideration to the factthat station readers outside the tray need to have orientations relativeto their transfer assemblies that are mirror images of orientations ofstation readers inside the tray relative to their transfer assemblies(since all discs in the tray have recording surfaces facing in the samedirection, and therefore must be laterally shifted in mirror imagedirections as they are loaded into station readers on opposite sides ofthe tray peripheries), the constructions shown in FIGS. 2-5 may also beconsidered representative of the constructions of stations locatedoutside the tray.

FIG. 2 shows the station and associated assemblies in an idle or "rest"position wherein neither the station nor its disc handling assembliesare handling a disc. FIG. 3 shows the station transfer assembly in a"pick out" position in which an aligning sub-assembly is acting toensure that a disc selected to be transferred is suitably aligned forthe transfer movement. FIG. 4 shows the transfer assembly in a loadingposition in which it is driving a disc from the tray to a positionfacing but lateral y displaced from the station reader. FIG. 5 shows thetransfer assembly in a read (processing) position out of contact with adisc that is ready to be moved into the station reader.

Referring to FIG. 2, the disc transfer assembly comprises a topdriveassembly 68 and a grooved stage 69. During disc loading and unloading,topdrive assembly 68 contacts and controllably drives a disc along itstop edges, while bottom edges of the same disc are held in and guided bya groove 69a in stage 69. The alignment between the topdrive assemblyand the groove in the stage ensures that the disc is driven in aperfectly vertical orientation and the structures of these elementsensures that the disc cannot stray from the required path of movement(i.e. that it cannot slip, slide, wobble, etc.) during its controlleddrive. Groove 69a is formed in an elastomeric material and has aV-shaped bottom tapered cross-section allowing for centered positioningof discs varying in thickness from approximately 0.042 to 0.056 inches(the range of presently standardized compact discs). The elastomer ingroove 69a is chosen to have a greater hardness than the elastomer intray grooves 2; since the purpose of groove 69a is to keep the bottomedges of the disc from deviating from the desired plane of transferrotation, without impeding the rotation, whereas grooves 2 in the trayare required to keep the discs properly seated during rotations of thetray (which exert inertial forces on the discs perpendicular to theirplenes of transfer rotation).

Topdrive assembly 68 is at the heart of the subject changer's fastoperation, allowing for very short loading and unloading times less than250 milliseconds. Assembly 68 includes a stamped overarm assembly 70,supporting a pair of pulleys 71 and 72, and a polyurethane belt 73riding on the pulleys. Assembly 68 also includes a stamped cam 74, aforward solenoid 75, a rear solenoid 76, and two guide/supportpillars--fulcrum pillar 77 and distal and column 78. A bidirectionalstep motor 79 (seen in FIG. 6), whose axis of rotation is at 80, ishoused on the fulcrum pillar. Step motor 79 drives belt 73 in oppositedirections (through pulley 72) during loading and unloading of a disc.The lateral center of belt 73 along its length is aligned with thetransfer plane over which the (centers of the) discs are to be driven.The belt is shaped in cross-section in the form of an inverted V (FIG.2C), for holding top edges of discs of different thicknesses, in theabove-mentioned standard range, in appropriate alignment to the requiredplane of rotation throughout the transfer movement, as well as forensuring correct alignment of discs that have their centers misalignedrelative to that plane when initially contacted by the belt.

Like groove 69a in stage 69, belt 73 has greater hardness than theelastomeric coating of the tray in which tray grooves 2 are formed, andis made of a material forming a slip-free contact with the top edges ofthe disc throughout the transfer movement.

Cam 74 is pivotally mounted on fulcrum pillar 77 with its center ofrotation around, but not driven by, step motor 79 (the step motor thatdrives belt 73). Cam 74 is attached to overarm assembly by (front) coilspring 81 arranged to cause the overarm to pivot in the same directionas cam 74 when the cam pivots.

In the "rest state" shown in FIG. 2, cam 74 is spring-loaded againststop 200 by rear spring 92, and overarm 70 rests on the lateral finger82 of the cam, preventing the overarm and belt 73 from contacting discscarried on tray 1 (e.g. while the tray is in motion). The bottom frontof cam 74 is attached to solenoid 75. A lead counterweight 95 isattached to the rear of overarm 70 and rear solenoid 76. With neither ofsolenoids 75 and 76 energized, the weight of the overarm's longextension is balanced by that of counterweight 95.

Upon energization of front solenoid 75, the front of cam 74 pivots down,lowering overarm 70 and belt 73 towards the tray (see FIG. 3). In thismovement, the inverted V underside of belt 73 (FIG. 2C) is brought intocontact with top edges of a disc 54 in the tray, in preparation forloading that disc. This pivotal movement of the overarm places thetransfer assembly in the "pick out" position shown in FIG. 3.

Referring to FIGS. 2 and 3, as arm 70 lowers from its rest position tothe pick out position, pick member 83 on the end of the arm engagesplastic comb 84 rotating the comb counter-clockwise. This causes teeth85 on the comb (see FIG. 2A), which are tapered to reliably captureopposite surfaces of the disc to be transferred, to sweep up and overopposite surfaces of the selected disc, from an initial position outsideof the periphery of that disc, and thereby straighten the disc tovertical alignment if the disc happens to be tilted when the combengages its surfaces. In most instances the discs in the tray will havesuitable vertical alignment prior to this operation. However, the combaction ensures such alignment in exceptional instances where discs thatare selected for loading have not properly seated in respective holdinggrooves 2 in the tray. The comb action completes just before belt 73reaches a position at which it is supposed to contact the top edge ofthe disc. Therefore, the top edge of the disc will reliably align withand be contacted by the inverted V grooved surface of belt 73 at theconclusion of the pick out movement.

The comb teeth are formed of a suitable low friction material minimizingthe possibility of damage to the recording surface of the disc, and theshape of the teeth and their path of movement during the alignmentensures that there will be minimal contact with the disc surfaces insideof a non-recording margin at the periphery of the disc.

The construction of the comb teeth allows for them to be moved to thepick-out position without waiting for any vibrations of the discs in thetray (e.g. due to inertia of the tray movement) to settle out. In fact,the comb teeth can be used at such times to quickly dampen anyvibrations of the selected disc and the discs adjacent to it.

When belt 73 contacts the top of the disc, the unsupported span of thebelt between pulley 71 and raceway 86 flexes longitudinally, allowingthe belt to wrap itself around a circumferential portion of the disc asseen in FIG. 3 thereby securing firm contact between the belt and thedisc, allowing the disc to be controllably and quickly accelerated fromits rest position in the tray.

As the underside of belt 73 contacts the top edge of a selected disc,step motor 79 is actuated to drive the belt. The step motor is driven bya programmable controller (made by Cybernetics Corporation). Said stepmotor is accelerated rapidly to drive the selected disc quickly, in aclockwise direction (as viewed in FIG. 2), to move it quickly out of itsholding groove in the tray onto groove 69a on stage 69, and then evenmore quickly over the stage to a load position at which the load/unloadassembly will take control of the disc and latch it into engagement witha rotatable spindle in the station reader (see description ofLoad/unload Assembly below). As the disc approaches this load positionthe step motor driving the belt is rapidly decelerated to bring the discto a safely controlled stop at the load position.

The energization of solenoid 75 (FIG. 2) actually causes the front ofcam 74 to lower more than the overarm, stretching spring 81. Thiscreates a downward force that is transferred to the area of contactbetween the belt and the top edge of the disc, creating more frictionbetween the belt and disc edge and thereby decreasing the possibility ofslippage during the rapid acceleration of the disc out of the tray.

As the disc is driven out of the tray, the arm rises to the positionshown in FIG. 4, retracting pick member 83 from contact with comb 84.This allows the comb to fall back clockwise to its rest position (FIG.2), where it is outside of the path of movement of the discs in thetray. Thus, as soon as a disc is moved out of the tray onto a stage suchas 69, (and potentially while the transfer rotation and load/unloadmovements of the same disc are still being handled), the tray can bemoved; e.g. to service another loading or unloading operation or toreposition the tray so that the disc just transferred can be unloaded toa groove in the tray different from the one from which it was removed(see discussion of sorting applications below).

As belt 73 is driven, a portion of its upper surface is held in andguided by a high molecular weight polyethylene raceway 86 attached tooverarm 70. This raceway presents a low friction surface guiding thebelt and preventing it from moving laterally or vertically. The racewayoverlies a portion of the stage, and the belt is unconstrained in thearea above the tray where it initially contacts the disc. Thus, the beltis free in that area to wrap itself into conformance with the discperiphery as explained previously, in order to secure sufficient contactwith the disc ensuring that the latter is properly controlled during itsinitial acceleration out of the tray groove.

In FIG. 4, topdrive arm 70 and belt 73 are shown in a load position inwhich belt 73 and a disc 54' transferred by the belt are both at astandstill but still in contact. At this position (see FIG. 6), stage 69contains a stepped depression opening into a shelf 69b that is alignedwith the groove 69a previously discussed. Shelf 69b opens into anotherdepression 90 which is below the station reader 99 and its spindle 98,the latter to be described later (see description of load/unloadassembly). The disc, which is now held upon ledge 69b by the belt and byparts of the load/unload assembly discussed below with reference toFIGS. 8-12, is required to be moved laterally over the depression 90 bythe load/unload assembly in order to engage the above-mentioned spindlein the opening at the center of the disc.

An infrared sensor 93 and a plastic stop 94 shown add further controland safety to disc handling. Stop 94 is positioned to prevent movementof the disc beyond the loading position (the position wherein the centeropening of the disc is aligned with a spindle in the station reader andthe disc itself is suitably aligned with the load/unload assembly to bereliably transferrable to the reader spindle. Sensor 93 operates todetect the leading edge of the disc as it rotates towards the loadingposition and to detect the trailing edge of the disc as the disc reachesthe loading position. The sensor provides signals useful to permit theapparatus to verify that a disc will be placed at the loading position.

In FIG. 5, topdrive arm 70 has been raised slightly by operation ofsolenoid 76 to raise belt 73 out of contact with the top edge of disc54', and disc 54' is shown held in a position in which it is underexclusive control of the load/unload assembly.

4. Dimensions

Some relevant dimensions of the foregoing apparatus are:

a) Tray circumference: 2000 mm (pitch line of 400 tooth belt)

b) Tray ID circumference: 1760 mm

c) Disc mean diameter: 120 mm

d) Disc mean thickness: 0.050 inches

5. Disc Handling Considerations

In respect to the foregoing, a number of disc handling factors should benoted.

First of all, a factor to consider is the hardness of the elastomer inwhich the tray grooves are formed. The material should be soft enough toexert the "elastic pinching" effect described previously, but not sosoft as to allow for the discs to shift or vibrate excessively duringmovements of the tray. A suitable hardness for the tray elastomer is ashore A value of 75-80.

The purpose of the elastomeric groove in the stage is only to guide thediscs, not to "elastically pinch" them, and present a non-slip surfaceto the bottom edges of the discs during their transfer rotations.Accordingly, the elastomer containing the groove in the stage can beharder than that containing the grooves in the tray (a suitable hardnessfor the stage elastomer would be a shore A value in the range 80-85).

Finally, the purpose of the inverted V groove in the belt is to bothguide and drive the disc top edges with minimal slip. A suitable formfor the belt groove is shown in FIG. 2C, and a suitable hardness for thesurface of the belt at that groove would be a shore A value in the range80 to 85.

6. Load/Unload Assembly

The load/unload assembly 100, described with reference to FIGS. 8-12,serves two purposes noted briefly above: (a) it holds the disc on shelf69b while the topdrive belt is being disengaged from the disc duringloading and re-engaged with the disc during unloading; and (b) itoperates to transfer the disc laterally (in a direction transverse toits path of movement by the topdrive belt) over the depression 90 andlatch the disc to a bull nosed rotatable magnetic spindle 98 that ispart of a compact disc reader (or reader/recorder) 99, the latter shownin block form in FIGS. 8-12. In the lateral transfer to spindle 98, acenter opening in the disc 54a is engaged to a matching boss on thespindle 98. In the lateral transfers between the loading position andthe spindle, the disc is moved from alignment with a vertical planeextending through shelf 69b to alignment with a vertical plane extendingthrough the tip of spindle 98, during loading, and from the spindle backto alignment with the vertical plane through the shelf during unloading.

In the embodiment shown, the discs are conventional compact discs and/orCD-ROMs (as known today), having predetermined widths and diameterswithin predetermined tolerances. Each such disc has arecorded/recordable side and a non-recordable opposite side. In thelateral movements of the discs between the shelf vertical plane andreader spindle, the recorded/recordable surface of the disc faces thespindle and the non-recordable surface faces towards the vertical risebetween shelf 69b and stage 69 (i.e. towards the load position on thestage).

During such lateral movements, the non-recordable side of the disc isheld against latch 101 retained movably within a keeper housing 102 (seeFIG. 10A). The latch is movable in three dimensions to adjust to planesin which the disc is oriented when it moves under control of thelatch/unlatch assembly, and when it is mounted on the reader spindle.

As indicated in FIG. 10A, latch 101 contains a flat piece ofmagnetizable sheet metal 101a imbedded in a plastic well 101b containingan opening 101c in its face 104 that conforms to the bullnose shape ofthe tip of the reader spindle 98. The spindle is magnetic (made of rareearth), and therefore attracts and holds latch 101 when the latter isclose to the spindle. A not-shown leaf spring in keeper 102 biases latch101 into a ready position (the position when assembly 100 is prepared toreceive an oncoming disc from the topdrive assembly) slightly tiltedacross the plane of movement of an oncoming disc so as to permit thelatch to easily align with the disc as the leading edge of the discpasses the latch.

Assembly 100 also includes upper and lower fingers (FIG. 6), 110 and 111respectively. During loading and unloading of a disc, these fingerscontact the data side of the disc, respectively along upper and lowernon-data marginal portions of that side, holding the disc against theface 104 of latch 101, with the center opening 54 of the disc facingwell opening 101c in latch 101. The forces exerted by the fingersagainst the disc preferably are sufficient to hold the disc securelyagainst the latch but insufficient to cause bending or flexing of thedisc. This is further assured by the presence of the back finger guide140 which acts as a limit to lateral overtravel of the top of the disc.

Fingers 110 and 111 have radiused tips, for smoothly engaging discsduring loading and disengaging from discs during unloading. The fingersare connected to a blue steel spring hinge 112 (FIGS. 8-12) that isattached to vertical latch base 120 (FIGS. 8-12). The fingers and latchbase are pivotable by two sets of cams 96a and 96b, both operated byrotary solenoid 96. One set of upper and lower cams 96a control fingers110 and 111 and one set of upper and lower cams 96b control latch arm121.

FIGS. 8-12 show positions of load/unload assembly 100 during a loadingoperation, as a disc is moved progressively from the tray to the loadposition over shelf 69b and then laterally over to the reader spindle.Viewed in the reverse order, these figures show the positions ofassembly 100 as a disc is moved progressively off the spindle to shelf69b and returned to the tray.

FIG. 8 shows assembly 100 at rest (disc still in tray). FIG. 9 shows theassembly in a "ready" position, prepared to receive a disc 54' that hasjust moved out of the tray. FIG. 10 shows the assembly in a "load"position with disc 54' engaged between the fingers and latch. FIG. 11shows the assembly in a "moved" position wherein the disc is mounted onspindle 98, but still in contact with the assembly fingers. FIG. 12shows the assembly in read/write position, with its fingers retracted(removed from contact with the disc) and the spindle, disc and latchthereby free to spin as a unit.

Load/unload assembly 100 is; rotated by rotary solenoid 96 which drivesfinger cam 96a and latch cam 96b. As shown in FIG. 8, the rotarysolenoid is in a power-off condition such that latch arm 121 and fingers110 and 111 (in this rest/power-off position) are urged clockwise by theinternal rotary return spring of rotary solenoid 96. FIG. 12 shows theload/unload assembly 100 in a power-off position, with a disc 54' in theread position on spindle 98 with fingers not contacting said disc inorder that it may spin freely. FIGS. 9 and 10 show rotary solenoid 96 ina powered position constructed and arranged such that cams 96a and 96bare rotated in a counter-clockwise direction (compared to FIG. 8),rotating both fingers 110 and 111 and latch arm 121 in a counterclockwise direction, to be in an open position to receive an oncomingdisc (FIG. 9). FIG. 11 is a snapshot of the load/unload assembly takenas latch arm 121 has completed its movement to the power-off positionand fingers 110 and 111 still have additional rotational movement (cam96a) to move to the power-off position.

In the assembly ready position (FIG. 9), face 104 of latch 101 isaligned to the path of movement of the oncoming disc, by the not-shownleaf spring within keeper assembly 102. In this position, the leadingedge of the oncoming disc (not visible in FIG. 9 but approachingassembly 100 from the left in that figure) is heading towards contactpoint 105 on latch 101 (see FIGS. 9 and 10A), and the latch face 104 ispositioned at an angle across the path of movement of the oncoming discso as to permit the latch to align easily with the disc. Shortlyafterwards, the leading edge of the oncoming disc is driven between thefingers 110, 111 and contact point 105 of latch 101. As the disccontinues to be rotationally driven towards its load position (centeredover shelf 69b in stage 69), it courses by the face 104 of the latchwith slight interference, tilting the face from its spring-biasedorientation and forcing the latch deeper into keeper 102.

In the load position of FIG. 10, the disc is held between the belt andshelf 69b of stage 69, with its center aligned with the reader spindle.The belt has stopped moving and thus the disc has stopped rotating. Thedisc is now in contact with both the belt and the fingers and latch ofassembly 100. As noted earlier, the pressure of the fingers against thedisc preferably is sufficient to hold the disc but not bend or flex it.As the disc reaches this position, the topdrive arm is raiseddisengaging the belt from contact with the disc by solenoid 76.

With the belt disengaged, assembly 100 is moved laterally towards thereader 99, by operation of rotary solenoid 96 and cams 96a and 96b,moving the disc into engagement with the spindle. This lateral movement,over a rather small distance (less than 1/16 inch) carries the disc offthe shelf 69b across the depression 90 (FIG. 6). The disc is securelyheld between the fingers and latch, and any (remote) possibility of thedisc slipping vertically (downward) towards the depression 90 is offsetby the engagement of the bull nosed radius of the spindle 98 to thecenter opening of the disc 54a, which would cause the disc to return tocentered alignment with the spindle even if it had slipped slightlydownward during the movement.

As seen in FIG. 11, assembly 100 has carried a disc 54' over to thespindle, and fingers 110 and ill are still in contact with the disc. Asseen in FIG. 12, the fingers have been pivoted out of contact with thedisc by cam 96a. The disc, spindle and latch are then free to rotate asa unit, and the not-shown reader motor that drives the spindle is "spunup".

After the disc has been read or otherwise processed, the disc isreturned to the tray in an unloading operation that is the reverse ofthe loading operation just described. First, the load/unload assembly ismoved from the position of FIG. 12 back to that of FIG. 11, with thefingers contacting the disc and exerting sufficient force to break themagnetic attraction between the spindle and latch so as to allow thedisc to return to the load position on shelf 69b. As the bottom edge ofthe disc moves onto the shelf 69b, and its non-data side banks upagainst the vertical rise 69c between the shelf and the top of stage 69,the top edge of the non-data side of the disc banks against back fingerguide 140 (FIG. 6) that is positioned opposite the upper finger 110which assists in aligning the disc vertically for the V groove of thetop drive belt which is brought down into contact with the disc anddriven in the reverse direction to drive the disc back to the tray.During this lateral movement, in the event the transferred disc shouldslip vertically downward, the bottom edge of the disc will engage theslope of depression 90 and the disc will be urged up the slope ofdepression 90 onto shelf 69b by fingers 100 and 111.

At this position, the topdrive belt is brought down into contact withthe disc and driven in the reverse direction to rotate the disc back tothe tray, where as shown in FIG. 2, over arm 68 will release fromcontact with said selected disc when said disc is safely returned to agroove 2.

7. Disc Repositioning

Normally, after a disc has been loaded and processed, it is returned tothe tray at the groove position from which it was loaded. The tray maybe moved while the disc is being read, to allow for aligning and loadingof other discs at other stations, and if it has moved it will bereturned to the position required to seat the unloaded disc in itsoriginal groove. However, in some instances, it may be desirable toreposition the tray and unload the disc to a groove in the traydifferent from the one it was in before it was loaded.

For instance, with the eight stations and tray shown and describedabove, it is possible to reposition discs relative to each other; forinstance, to place frequently loaded discs closer to the stations thanless frequently loaded discs, and thereby reduce the average seek timefor positioning discs to be loaded in line with stations.

In such "sorting" operations, assuming all grooves in the tray arefilled with discs, one could manipulate the system to load 8 discs froma group of 8 grooves/slots into the 8 stations, and then selectivelyunload the discs to the same group of slots but at different slotpositions so that the positions of the discs relative to a given stationare varied as a function of the history of usage of respective discs,placing discs most frequently loaded nearest to stations and discs leastfrequently loaded furthest from stations.

8. Operational Flow Sequence

In a typical operation of the subject apparatus, wherein informationcontained on discs is to be read at the stations, the apparatus receivesrequests for information and translates them into locations of groovesin the tray holding discs containing the requested information. For eachrequest, the tray is repositioned to align the groove holding the discthat contains the requested information with a nearest idle one of theeight stations. Obviously, this repositioning step could be skipped ifthe desired disc is aligned to a station when the request is beinghandled. Next, the transfer mechanism of the respective station isactuated, controllably driving the disc out of the groove and into therespective station, then the load/unload assembly at the station securesthe disc to the station spindle, the requested information is read out,and the disc is unloaded back to the tray by reversed operations of theload/unload assembly and transfer mechanism.

The source of the foregoing requests is immaterial to the invention. Butthose skilled in the art should recognize that it could be a computerserver linked to multiple users through a network, or even a personalcomputer owned by a single user of that computer and the subjectapparatus.

The repositioning of the tray to align the requisite groove with thenearest idle station could be specified as a product of numbers n and k;where n is a variable defining the number of groove spaces between therequired groove and the nearest station and k is a constant related tothe number of increments of tray movement required to displace the trayby a single groove spacing. That number would be applied to the controlsof the step motor that drives the tray, and the tray then could be movedthrough the requisite distance in an appropriateacceleration/deceleration pattern.

As noted earlier, as soon as a selected disc is moved out of its grooveby a transfer mechanism, the aligning comb 84 (FIG. 2) drops out of theway permitting further movement of the tray. Thus, while a selected discis being moved into the station, secured for reading and read, the traymay be simultaneously moved to prepare discs associated with otherrequests for handling.

As also noted earlier, a disc unloaded from a station may be returnedeither to the groove from which it was loaded or a different groove,depending upon requirements of the system in which the apparatus isused.

Alternate Embodiments

Alternate embodiments of the invention presently contemplated include:a) apparatus in which the tray is a part (e.g. a 90 degree section) ofthe tray heretofore described, holding fewer discs, and operatingrelative to fewer stations, where the station and its transfer andload/unload assemblies rotates relative to the tray to align with a discto be transferred; and b) a linear configuration wherein the tray hasrectangular form and is moved linearly relative to one or more stationspositioned on opposite sides of the path of tray movement.

Variations of these alternate embodiments are also considered within thescope of the invention and its claims.

For example, although the preferred embodiment has a circular tray thatis rotated relative to the stations, it is also considered feasible toarrange for the stations and their disc handling assemblies to berotated relative to a stationary tray to accomplish the same functions.

Another alternative includes a tray design, with stations as previouslydescribed and a circular tray as described, however, this design savesspace in the over all dimensional width of the circular tray, where asmaller overall diameter of e.g. 15 inches allows storage of the entireunit in standard 21 inch equipment racks. The smaller diameter isrealized by placing a smaller number of grooves in the tray, e.g. 240grooves around the circular tray that are aligned at oblique angles tothe radius edge of the circular tray as shown in FIG. 13. In thisembodiment, the four stations 20s, 21s, 22s, and 23s plus four transferassemblies 20t, 21t, 22t, and 23t are arranged toward the outsideperiphery of the tray such that the a disc is driven to a stage andload/unload assembly and reader, outside of the tray's perimeter. FIG.13, where possible is marked using prime numbers to indicate thesimilarity of operation to the corresponding numbered figures.

As shown in FIG. 13, a tray 1' has a circular shaped inner and outerperiphery, said inner periphery 5 coinciding with at least a portion ofthe circumference of a first circle and said outer periphery 1a'coinciding with at least a portion of the circumference of a secondcircle. The tray has linear grooves 2' (shown as lines in FIG. 13)formed in a surface thereof for holding multiple disc in closeproximity. Each groove forms a predetermined oblique angle with a radiusof one of said first and second circles at a point on the respective oneof said first and second circles at which the respective groove andradius intersect disc processing station e.g. 20s proximate to one ofsaid inner and outer peripheries of said tray includes means for movinga disc between any selected one of said grooves in said tray and saiddisc processing station.

The disc processing station includes a predetermined disc loadingposition proximate to a predetermined fixed point on one of said firstand second circles and includes means for moving a disc between anyselected one of said grooves. The disc processing station includes meansfor effecting relative movement between said tray and said loadingposition of said station to position an end of a said any selectedgroove in said tray adjacent to said predetermined fixed point.

The predetermined disc loading position is aligned with said anyselected groove in said tray at said predetermined fixed point when saidany selected groove is positioned with an end thereof adjacent to saidpredetermined fixed point by operation of said means for effectingrelative movement. There is a means for driving said disc between agroove holding said disc and said predetermined loading position, usingthe top drive assembly previously described when said end of the grooveholding said disc has been positioned adjacent said predeterminedloading position by said means for effecting relative movement. Saidtray can preferably operate with the identical transfer assembly andload/unload assembly, stations and processing stations as previouslydescribed herein.

Wherefore, I claim:
 1. Automatic disc changer apparatus comprising:abase structure; a tray supported on said base structure for holdingmultiple record discs in close proximity to each other; a discprocessing station supported on said base structure; said processingstation containing a predetermined disc loading position; means totransfer a selected disc from said tray to said predetermined discloading position of said processing station in a controllably drivenrotational movement; said transfer means including a flexible belthaving a portion of its length overlying both said tray and saidpredetermined disc loading position, means to bring said flexible beltinto contact with a top edge portion of said selected disc, and meansfor moving said flexible belt lengthwise to controllably drive saidselected disc between said tray and said disc loading position in arotational movement of said disc; and means for effecting relativemovement between said tray and said predetermined disc loading positionto align a said selected disc in said tray with said predetermined discloading position; said apparatus further including: a latch elementattractable magnetically to said spindle, a pair of movable guidefingers, means for initially positioning said guide fingers and saidlatch element to contact and bear against opposite surfaces of saidselected disc as said disc enters said predetermined disc loadingposition, while being driven by said flexible belt, allowing saidflexible belt to be immediately disengaged from contact with said topportion of said selected disc as said disc is moved into saidpredetermined loading position; and means to move said fingers and latchelement, with said selected disc held between them, to bring the latchelement and disc into magnetically latched contact with said spindle,and simultaneously disengage said guide fingers from contact with saiddisc, in order to allow said spindle, disc and latch element to befreely rotated as a unit.
 2. Automatic disc changer apparatuscomprising:a base structure; a tray supported on said base structure forholding multiple discs in close proximity; a reading station supportedon said base structure; said reading station having a predetermined discloading position; means for effecting relative movement between saidtray and said predetermined disc loading position to align any selecteddisc one of said discs on said tray with a plane extending through saidtray and said predetermined disc loading position; means forcontrollably driving said selected disc, in alignment to said extendingplane, to move said selected disc from said tray to said predetermineddisc loading position; said means for driving maintaining precisecontrol over the orientation and speed of movement of said selected discthroughout said movement from said tray to said loading position; saiddriving means further comprising:an arm extending over said tray andsaid predetermined disc loading position; a flexible belt supported onsaid arm; said belt extending lengthwise over said tray and said loadingposition, and having its lengthwise center lying in said extendingplane; said belt being supported for linear movement of its saidlengthwise center in said extending plane; means for moving said arm andsaid belt towards and away from said tray for placing said belt in andout of lengthwise contact with a top edge portion of a said selecteddisc in said tray; means for linearly moving said flexible belt, whilesaid belt is in lengthwise contact with said top edge portion of a saidselected disc, to rotationally drive said selected disc out of said trayand over to said predetermined loading positions; means aligned withsaid extending plane, within said tray and between said tray and saidloading position, for securely holding and guiding a bottom edge portionof said selected disc as that disc is being rotationally driven by saidbelt from said tray to said loading position, thus constraining saidselected disc to rotate in alignment with said extending planethroughout the rotational movement of that disc from said tray to saidloading position; and disc aligning means, actuated in coordination withsaid movement of said arm and belt towards said tray, for ensuring thatsaid top edge portion of said selected disc is aligned to saidlengthwise center of said belt prior to said arm and belt reaching apoint in their movement at which the belt could contact said selecteddisc; said disc aligning means comprising:a pick element suspended fromsaid arm; and a comb element aligned with said predetermined loadingposition, said comb element having a pair of spaced teeth positionedoutside of the periphery of said selected disc prior to said movement ofsaid arm and flexible belt towards said tray;said pick element engagingsaid comb element, during said movement of said arm and flexible belttowards said tray, to cause said teeth of said comb element to passacross opposite surfaces of said selected disc and align said selecteddisc to said extending plane if said selected disc was previouslymisaligned to that plane, thereby causing said top edge portion of saidselected disc to be placed in alignment with said lengthwise center ofsaid belt if said top edge portion was previously misaligned to saidlengthwise center.